Optical pumping studies in He⁴ with a tunable color center laser

Optical pumping is a very useful technique for the production of spin polarized Helium ions and metastables. The optical pumping process requires a source of near infrared radiation resonant with the transitions, such as can be provided by a high power rf Helium discharge. This thesis describes the development of a tunable infrared color center laser which is ideally suited to study the optical pumping process in Helium. The laser, which uses the color center in NaF, is based on a novel cavity design which allows for operation in either a linear configuration or a ring configuration. An analysis of the stability considerations relevant to this dual configuration approach is presented. An experiment in which the laser was used to measure the spin polarization of an optically pumped Helium discharge is described in detail. Additional optical pumping experiments are also outlined